Aerodynamic front fork for a bicycle

ABSTRACT

An aerodynamic front fork assembly for a bicycle may include an elongated crown portion extending from a steerer tube to a distal end behind a front wheel, with one or more fork blades projecting in a generally forward direction from the distal end of the crown portion to engage the front wheel. The crown portion may substantially fill the gap between the front wheel and the down tube of the bicycle, thereby collectively forming an airfoil with the front wheel and the down tube.

INTRODUCTION

The aerodynamic drag of a bicycle is an important factor affecting speedin competitive cycling events, such as triathlons, time trials, and thelike. Reducing drag leads to higher speeds and better competitiveresults. Accordingly, improvement in the aerodynamic design of bicyclesand bicycle components is highly desirable.

An airfoil is a teardrop shape that is used in fluid dynamicapplications such as airplane wings, sailboats, and bicycle componentsto reduce drag. Another factor in reducing drag is the reduction offrontal area of the surface or surfaces that are exposed to airflow.Various bicycle designs incorporating airfoil shapes into frames havebeen introduced over the years. Attempts to address the issues of drag,turbulence, and speed have met with varying levels of success.

SUMMARY

The present disclosure provides systems, apparatuses, and methodsrelating to aerodynamic front fork assemblies for bicycles. In someembodiments, a front fork for a bicycle may include: a steerer tube; anelongate crown coupled to the steerer tube, the crown extending at anoblique angle from a proximal end portion adjacent the steerer tubethrough an intermediate portion to a distal end portion, and extendingfrom a rear face to a front face, the rear face having a linearlengthwise profile, and the front face having an arcuate lengthwiseprofile; and one or more fork blades extending in a generally forwarddirection from the distal end portion of the crown, each of the one ormore fork blades having a distal end; wherein the front fork isconfigured to receive a front wheel of a bicycle, the front wheel beingreceived by the distal ends of the one or more fork blades, the rearface of the crown generally conforming to an adjacent down tube of thebicycle, and the front face of the crown being adjacent to an outerperimeter of the front wheel, such that the crown substantially fills agap between the front wheel and the down tube.

In some embodiments, a bicycle may include: a frame including a downtube; a front wheel steerably coupled to the frame by a front fork, thefront fork comprising: a steerer tube pivotably coupled to a head tubeof the frame; a crown having a proximal end portion coupled to thesteerer tube, the crown extending generally parallel to the down tube toa distal end portion behind the front wheel, the crown having a pair ofside walls extending continuously from a front face that generallyfollows a curved outer circumference of the front wheel to a rear facethat generally follows a linear front surface of the down tube, whereinthe crown substantially fills a gap between the front wheel and the downtube; and one or more elongate fork blades protruding in a generallyforward direction from the distal end portion of the crown, the frontwheel being rotatably coupled to the one or more fork blades.

In some embodiments, a bicycle may include a frame including a downtube; a front wheel steerably coupled to the frame by a front fork, thefront fork comprising: a steerer tube pivotably coupled to a head tubeof the frame; a crown having a proximal end portion coupled to thesteerer tube, the crown extending generally parallel to the down tube toa distal end portion behind the front wheel, the crown having a pair ofside walls extending continuously from a front face that generallyfollows a curved outer circumference of the front wheel to a rear facethat generally follows a front surface of the down tube, wherein thecrown substantially fills a gap between the front wheel and the downtube; and one or more elongate fork blades protruding in a generallyforward direction from the distal end portion of the crown, the frontwheel being rotatably coupled to the one or more fork blades.

Features, functions, and advantages may be achieved independently invarious embodiments of the present disclosure, or may be combined in yetother embodiments, further details of which can be seen with referenceto the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of an illustrative bicycle andaerodynamic front fork assembly in accordance with aspects of thepresent disclosure.

FIG. 2 is an oblique isometric view of an illustrative aerodynamic frontfork assembly, with a bicycle drawn in dashed line to indicaterelationships between components.

FIG. 3 is a sectional view of a front wheel, front fork assembly, anddown tube of the bicycle of FIG. 1, taken at line 3-3 and showing theoverall airfoil shape of this combination of components.

FIG. 4 is another sectional view of the components of FIG. 3, taken atline 4-4 in FIG. 1 and showing the relative motion between the fork andthe down tube when steering the front wheel.

FIG. 5 is a schematic exploded view of an illustrative front forkassembly according to the present teachings.

FIG. 6 is a side elevation view of another illustrative bicycleincluding an aerodynamic front fork assembly in accordance with aspectsof the present disclosure.

FIG. 7 is a side elevation view of another illustrative bicycleincluding an aerodynamic front fork assembly in accordance with aspectsof the present disclosure.

FIG. 8 is a sectional view of the front wheel, front fork assembly, anddown tube of the bicycle of FIG. 7, taken at line 8-8 and showing theoverall airfoil shape of this combination of components.

FIG. 9 is a side elevation view of yet another illustrative bicycleincluding an aerodynamic front fork assembly in accordance with aspectsof the present disclosure.

FIG. 10 depicts a sectional view taken through the wheel, front forkassembly, and down tube of the bicycle of FIG. 9, taken at 10-10 andshowing the overall aerodynamic shape.

FIG. 11 is a perspective view of another illustrative bicycle includingan aerodynamic front fork assembly in accordance with aspects of thepresent disclosure.

FIG. 12 is a front elevation view of the bicycle of FIG. 11.

FIG. 13 is a partial side elevation view of an illustrative dampingmechanism suitable for use with front forks according to the presentteachings.

FIG. 14 is a sectional view taken at 14-14 in FIG. 13.

FIG. 15 is a sectional view taken at 15-15 in FIG. 13.

FIG. 16 is a flow chart depicting steps in an illustrative manufacturingprocess in accordance with aspects of the present disclosure.

DESCRIPTION

Various aspects and examples of an improved aerodynamic front forkassembly for a bicycle, as well as related systems and methods, aredescribed below and illustrated in the associated drawings. Unlessotherwise specified, an aerodynamic front fork assembly and/or itsvarious components may, but are not required to, contain at least one ofthe structure, components, functionality, and/or variations described,illustrated, and/or incorporated herein. Furthermore, unlessspecifically excluded, the process steps, structures, components,functionalities, and/or variations described, illustrated, and/orincorporated herein in connection with the present teachings may beincluded in other similar devices and methods, including beinginterchangeable between disclosed embodiments. The following descriptionof various examples is merely illustrative in nature and is in no wayintended to limit the disclosure, its application, or uses.Additionally, the advantages provided by the examples and embodimentsdescribed below are illustrative in nature and not all examples andembodiments provide the same advantages or the same degree ofadvantages.

Definitions

The following definitions apply herein, unless otherwise indicated.

“Substantially” means to be essentially conforming to the particulardimension, range, shape, concept, or other aspect modified by the term,such that a feature or component need not conform exactly. For example,a “substantially cylindrical” object means that the object resembles acylinder, but may have one or more deviations from a true cylinder.

“Comprising,” “including,” and “having” (and conjugations thereof) areused interchangeably to mean including but not necessarily limited to,and are open-ended terms not intended to exclude additional, unrecitedelements or method steps.

Terms such as “first”, “second”, and “third” are used to distinguish oridentify various members of a group, or the like, and are not intendedto show serial or numerical limitation.

Directional terms, such as “forward,” “rearward,” “front,” and “rear”(and the like) are intended to be understood in the context of a hostvehicle (e.g., bicycle) on which systems described herein may be mountedor otherwise attached. For example, “outboard” may indicate a relativeposition that is laterally farther from the centerline of the vehicle,or a direction that is away from the vehicle centerline. Conversely,“inboard” may indicate a direction toward the centerline, or a relativeposition that is closer to the centerline. Similarly, “forward” meanstoward the front portion of the vehicle, and “rearward” means toward therear of the vehicle. In the absence of a host vehicle, the samedirectional terms may be used as if the vehicle were present. Forexample, even when viewed in isolation, a fork crown may have a “front”side, based on the fact that the fork would be installed with the sidein question facing in the direction of the front portion of a hostbicycle.

“Coupled” means connected, either permanently or releasably, whetherdirectly or indirectly through intervening components.

Overview

In general, an aerodynamic front fork according to the presentdisclosure may include a space-filling crown portion extending from aproximal end at the steerer tube around a back portion of the frontwheel, where a pair of fork blades extends from a distal end of thecrown portion behind the front wheel in a generally forward direction.

Aerodynamic front forks according to the present teachings include awheel support structure configured to reduce drag on the forward area ofa bicycle by (a) reducing the frontal area of the components supportingthe front wheel and (b) integrating these components into a singleoverall airfoil shape. The present disclosure describes an extendedcrown portion of the wheel support structure integrated into a combinedassembly with a front wheel and the down tube portion of a bicycle frameto reduce frontal area and aerodynamic drag as compared to conventionalvertical forks.

Known bicycles typically support the front wheel on two generallyvertical blades (e.g., slightly inclined in the range of 10 to 20degrees from vertical). These blades are connected to a crown assemblythat couples the blades to each other and directly to a steerer tube,which is inclined similarly to the blades. Accordingly, conventionalfork blades are essentially fully exposed in the airstream throughouttheir lengths, on either side of the front wheel.

In contrast, aerodynamic front forks disclosed herein have blades thatare much closer to horizontal, e.g., angled between about 90 degrees toabout 50 degrees from vertical, thereby exposing much less surface areato the air stream. In some examples, the blade angle is approximately 80degrees from vertical, i.e., approximately 10 degrees from horizontal(e.g., eleven degrees from horizontal). In addition, the blades areconnected to a modified, elongated crown (e.g., approximately sixteeninches in length) between the blade connection point at a lower, distalend and the steerer tube to which it is connected at an upper, proximalend. The crown also extends in a generally downward and rearwarddirection, substantially parallel to the inclined down-tube of thebicycle frame. In addition to connecting the fork blades to the steerertube in a manner that produces the fork blade angle described above, thecrown is shaped and sized to substantially fill the gap between therearward portion of the front wheel and the front part of the down-tube,thereby effectively eliminating spaces and air pockets which can induceair turbulence and increase drag. This adds further to the aerodynamiceffect of the overall assembly.

Front wheel support assemblies described herein may be integrated with anumber of existing bicycle frame down tube profiles, including ateardrop profile as well as a squared-off airfoil sometimes referred toas a Kamm profile after the German engineer Wunibald Kamm. In someexamples, an additional controllable trim tab element is integrated intothe overall assembly to reduce aerodynamic drag by increasing the aspectratio or aerodynamic chord of the assembly. The trim tab can be used toreduce heel or lateral movement of the bicycle that can sometimes becaused by cross winds. Controllability of the trim tab may be effectedmanually and/or by a sensor and actuator mechanism that automaticallyoptimizes its angle based on wind speed and direction.

Examples, Components, and Alternatives

The following sections describe selected aspects of exemplaryaerodynamic front fork assemblies for bicycles, as well as relatedsystems and/or methods. The examples in these sections are intended forillustration and should not be interpreted as limiting the entire scopeof the present disclosure. Each section may include one or more distinctembodiments or examples, and/or contextual or related information,function, and/or structure.

A. First Illustrative Aerodynamic Front Fork Assembly and Bicycle

As shown in FIGS. 1-5, this section describes a first illustrativeembodiment of a front fork assembly, namely front fork assembly 10.Front fork assembly 10 is an example of the front fork assemblydescribed in the Overview above, and may also be referred to as a frontfork, a wheel support structure, or a wheel support assembly.

FIG. 1 is a side elevation view of a bicycle 12 suitable for use withfront fork assembly 10. FIG. 2 is an oblique isometric view of frontfork assembly 10, with bicycle 12 drawn in dashed line to indicate thefork's relationship to other components. FIG. 3 is a sectional view of afront wheel of bicycle 12, a portion of front fork assembly 10, and adown tube of bicycle 12, taken at line 3-3 in FIG. 1 and showing theoverall airfoil shape of this combination of components. FIG. 4 isanother sectional view of the components of FIG. 3, taken at line 4-4 inFIG. 1 and showing the relative motion between the fork and the downtube when steering the front wheel. FIG. 5 is a schematic exploded viewof front fork assembly 10.

With continuing reference to FIGS. 1-5, bicycle 12 includes forkassembly 10 and a frame 14. In this example, frame 14 comprises multipleframe elements, including a top tube 16, a down tube 18, and a seat tube20. Other examples, including those described below, may include more orfewer frame elements. As with many time-trial style bikes, down tube 18and seat tube 20 in this example have teardrop or airfoil crosssections, to reduce drag on the bicycle when in use. Down tube 18extends at an angle from a head tube 22 to a bottom bracket 24 ofbicycle 12. In this example, a leading edge 26 of down tube 18 issubstantially linear. However, other designs may be suitable for usewith fork assemblies in accordance with the present disclosure (e.g.,down tubes having a curved leading edge).

A front wheel 28 of bicycle 12 is steerably coupled to frame 14 by frontfork 10. More specifically, front fork 10 includes a steerer tube 30pivotably coupled to head tube 22, and an elongate crown 32 having aproximal end portion 34 coupled to the steerer tube, the crown extendinggenerally parallel to down tube 18 through an intermediate or midportion 36 to a distal end portion 38 behind front wheel 28. One or more(in this case two) fork blades 40 protrude in a generally forwarddirection from distal end portion 38. Front wheel 28 is rotatablycoupled to blades 40, e.g., by an axle of the wheel.

Crown 32 has a pair of side walls 42, 44 (also referred to as lateralfaces) extending continuously from a front face 46 that generallyfollows a curved outer circumference of front wheel 28 to a rear face 48that generally follows the front surface (i.e., leading edge 26) of thedown tube. Crown 32 is sized and shaped such that the outer perimeter ofthe crown substantially fills a gap 50 between the front wheel and thedown tube.

Substantially filling gap 50 may include any suitable taking-up of thespace between the wheel and the down tube, such that wheel 28, crown 32,and down tube 18 collectively form an airfoil when the front wheel isaligned with the down tube. In other words, the substantial filling ofgap 50 is sufficient to improve the aerodynamic characteristics in thevicinity of the down tube. In some examples, such aerodynamic effectsare achieved when the crown fills gap 50 by at least approximately 75percent, as measured from wheel to down tube. Less than that amounttends to produce undesirable turbulence and drag.

In some examples, a much greater filling effect is provided. Forexample, as shown in FIG. 1, only a narrow first space 52 is leftbetween front face 46 of crown 32 and an outer diameter of front wheel28. First space 52 may have any suitable dimension, e.g., approximately⅜ of an inch plus or minus ⅛ inch, and may vary from proximal portion 34to distal portion 38. Similarly, a narrow second space 54 is providedbetween rear face 48 of crown 32 and leading edge 26 of down tube 18.Second space 54 may have any suitable dimension, e.g., approximately ¼of an inch plus or minus ⅛ inch, and may vary from proximal portion 34to distal portion 38.

Accordingly, crown 32 may fulfill at least two functions: to reduce theaerodynamic impact of fork blade(s) 40 by positioning the proximal endof the fork blade(s) behind front wheel 28, thereby changing the forkangle, and to improve the aerodynamic profile of bicycle 12 bysubstantially filling gap 50.

In some examples, such as the one depicted in FIG. 1, a fork angle α maybe defined as the angle created by a longitudinal axis 56 of fork(s) 40with respect to horizontal. As described in the Overview section,bicycles typically have a fork angle of approximately 70-80 degrees. Inthe example of front fork 10, fork angle α is approximately ten degrees(e.g., eleven degrees) from horizontal. This slight angle permits theproximal end of fork(s) 40 to be higher up off the ground and fartherforward (as compared with a completely horizontal fork angle), therebybetter avoiding interference with a set of rotating cranks 58 and pedals60.

In some examples, e.g., as shown in FIG. 1, down tube 18 includes a downtube extension 62 protruding forward from the lower end of the down tubeto at least partially fill the space between bottom bracket 24 anddistal portion 38 of crown 32. As shown in FIG. 1, down tube extension62 may have a generally triangular profile when viewed from the side. Insome examples, extension 62 is coupled to down tube 18. In someexamples, extension 62 is unitary with down tube 18. In some examples,down tube 18 and extension 62 are formed as a single piece, creating amonolithic structure. A forward face 64 of extension 62 is adjacentdistal portion 38 of crown 32. One or more additional mechanisms may beincorporated into extension 62, such as the damper assembly describedbelow in Section E.

A long axis 66 of steerer tube 30 may have any suitable angle, includingstandard steerer tube angles used with conventional forks. As depictedin the example shown in FIG. 2, long axis 66 of the steerer tube passesforward of the distal ends of fork blade(s) 40. Furthermore, in thisexample, long axis 66 intersects with a support surface 68 (e.g., theground) at an intersection point 70 forward of a contact patch 72 offront wheel 28. In some examples, long axis 66 may pass through orbehind the axis of rotation of the front wheel, while still intersectingat a point forward of contact patch 72.

FIG. 3 depicts a sectional view through wheel 28, mid portion 36 ofcrown 32, and down tube 18, showing the overall aerodynamic shape of theairfoil collectively formed by these components. Wheel 28 includes a rim74 and a tire 76. Rim 74 may include any suitable bicycle wheel rim. Inthe examples described herein, where front fork assembly 10 is mountedon time trial bikes, rim 74 will often be of the aero style, e.g.,having a U-shaped, V-shaped, or hybrid toroidal sectional profile. Wheel28 may further include a braking system, such as a disc 78 mounted onwheel 28 and a corresponding disc brake 80 mounted on blade 40.

Front face 46 of crown 32 is adjacent tire 76, and is concave, with acurvature oriented transverse to its arcuate lengthwise profile. Thisallows the crown to hug (or partially wrap around) the front wheel.Front face 46 conforms generally to the outer surface of wheel 28, whichis circular overall but also presents a convex, rounded tire surface.

As depicted in FIG. 3, crown 32 has opposing lateral faces 42 and 44,which are configured and spaced from each other such that substantiallycontinuous opposing lateral surfaces are formed from a leading edge 82of front wheel rim 74 to a trailing edge 84 of the down tube 18. In thisexample, rear face 48 of crown 32 is generally planar. However, rearface 48 may instead be concave, convex, or otherwise shaped to conformmore or less with down tube 18. In some examples, crown 32 may include aspacer 86, which is a fairing or strip coupled (e.g., adhered) to therear face of the crown. Spacer 86 may include any suitable resilientmaterial having a thickness (e.g., a variable thickness) configured toat least partially fill gap or space 54 between the crown and the downtube when the front wheel is aligned with the down tube. In thisexample, spacer 86 has a rear-facing outer surface 90 comprising aresilient pile. In some examples, this resilient pile may besubstantially similar to the looped pile of one side of a hook-and-loopfastener.

Crown 32 comprises an outer shell 92, which may include any suitablestructure configured to structurally provide the outer shape and size ofthe crown, and may comprise any suitably strong yet lightweightmaterial, such as aluminum. In some examples, shell 92 may comprise acomposite material, e.g., carbon fiber. Crown 32 may be hollow orpartially hollow. In some examples, as indicated in FIG. 3, crown 32 maycomprise a solid core 94 surrounded by shell 92. Solid core 94 maycomprise any suitable material, such as a foam, a plastic, or a woodmaterial. In this example, core 94 comprises balsa wood, and may includea plurality of end-grain balsa wood blocks that are glued together in astack and machined to the proper shape (see manufacturing methoddescribed in Section F, below). The resulting crown 32 has a hightorsional stiffness. A grain of the wood may be oriented generallyparallel to a long axis of crown 32 to further enhance stiffness.

Although fork assembly 10 has a unique shape and configuration, steeringof bicycle 12 is relatively standard with respect to the experience of arider, because the steerer tube is oriented at an angle similar to atypical steerer tube. However, distal portion 38 of crown 32 and theproximal ends of fork blade(s) 40 do swing from side to side whenturning front wheel 28, as illustrated in FIG. 4. Normal steeringsituations, especially during use in a time trial or other bicycleracing situation, will not typically require steering of the front forkassembly to the degree shown in FIG. 4. Front wheel 28 will typically bemore or less aligned with down tube 18 during most operationalsituations.

FIG. 5 is an exploded view of front fork assembly 10, showing steerertube 30, shell 92, core 94, and a blade assembly 96 comprising twoblades 40 connected at a proximal end to a blade stub tube 98. Bladeassembly 96 may include any suitable wheel support structure configuredto extend from distal portion 38 of crown 32 in a generally forwarddirection, and to securely and rotatably receive front wheel 28 in thedistal ends of one or more fork blades (e.g., blades 40). Blade assembly96 may comprise carbon fiber and/or any other suitable material. Asshown in FIG. 5, the fork ends of blades 40 may include apertures forreceiving an axle or hub of front wheel 28. In some examples, blades 40may include dropouts or fork-ends for this purpose. Blades 40 may begenerally straight, or in some examples may include one or more curvedportions.

When assembled, the components of fork assembly 10 are secured together,such that fork assembly 10 is a solid, unitary structure having a hightorsional stiffness as compared to existing fork structures that areintended to be resilient or shock-absorbing. Shell 92 encases and wrapstightly around core 94, and encompasses steerer tube 30 at one end andstub tube 98 at the other end. Additional components may be utilized tohelp secure the structure together, such as a steerer receiver 100 and astub tube receiver 102. See the illustrative manufacturing methoddescribed in Section F.

As depicted in this and other examples, crown 32 may have an overallshape that is wider or thicker (e.g., from front to back) at proximaland distal portions 34, 38 than it is at mid portion 36. This isgenerally due to gap 50 having a corresponding shape, which results fromfront wheel 28 having a round or circular profile, while down tube 18has a straight or linear profile. Accordingly, crown 32 has a varyingdistance between front face 46 and rear face 48. However, in someexamples, leading edge 26 of down tube 18 may be curved. In thoseexamples, crown 32 may have a correspondingly curved rear profile, whichmay result in less variability in front-to-rear thickness, or even asubstantially constant distance between front face 46 and rear face 48.

B. Second Illustrative Aerodynamic Front Fork Assembly and Bicycle

As shown in FIG. 6, this section describes a second illustrativeembodiment of a front fork assembly. Front fork assembly 110 is anotherexample of the front fork assembly described in the Overview above, andis similar to fork assembly 10 of Section A. Front fork assembly 110 maybe referred to as a front fork, a wheel support structure, or a wheelsupport assembly. Except where specifically depicted or describedotherwise, components of the fork and bike described in this Section Bmay be substantively and functionally identical to correspondingcomponents described in Section A.

FIG. 6 is a side elevation view of a bicycle 112, which includes forkassembly 110 and a frame 114. In this example, frame 114 comprisesmultiple frame elements, including a top tube 116, a down tube 118, anda seat tube 120. As with bicycle 12, down tube 118 and seat tube 120 inthis example have teardrop or airfoil cross sections, to reduce drag onthe bicycle when in use. Down tube 118 extends at an angle from a headtube 122 to a bottom bracket 124 of bicycle 112. In this example, aleading edge 126 of down tube 118 is substantially linear.

As with bicycle 12, a front wheel 128 of bicycle 112 is steerablycoupled to frame 114 by front fork 110. An elongate crown 132 has aproximal end portion 134 coupled to the steerer tube. The crown extendsgenerally parallel to down tube 118 through an intermediate or midportion 136 to a distal end portion 138 behind front wheel 128. One ormore fork blades 140 protrude in a generally forward direction fromdistal end portion 138, and front wheel 128 is rotatably coupled toblades 140. In this example, blades 140 are substantially horizontal(e.g., having an approximately zero degree fork angle).

As with crown 32, crown 132 has a pair of side walls 142 (also referredto as lateral faces) extending continuously from a front face 146 thatgenerally follows a curved outer circumference of front wheel 128 to arear face 148 that generally follows the front surface (i.e., leadingedge 126) of the down tube. Crown 132 is sized and shaped such that theouter perimeter of the crown substantially fills a gap 150 between thefront wheel and the down tube, as described in Section A above.

As shown in FIG. 6, a narrow first space 152 is left between front face146 of crown 132 and an outer diameter of front wheel 128. First space152 may have any suitable dimension, e.g., approximately ⅜ of an inchplus or minus ⅛ inch, and may vary from proximal portion 134 to distalportion 138. Similarly, a narrow second space 154 is provided betweenrear face 148 of crown 132 and leading edge 126 of down tube 118. Secondspace 154 may have any suitable dimension, e.g., approximately ¼ of aninch plus or minus ⅛ inch, and may vary from proximal portion 134 todistal portion 138.

Unlike fork assembly 10, a long axis 156 of each blade 140 of forkassembly 110 is substantially horizontal. To achieve this angle, distalportion 138 of crown 132 must drop lower behind front wheel 128, ascompared to the example in Section A. However, the concern remainsregarding interference with a set of rotating cranks 158 and pedals 160,and crown 132 must be configured to ensure the crown remainssufficiently forward of bottom bracket 124. Accordingly, rear face 148of crown 132 drops down in a substantially vertical fashion, such thatcrown 132 includes a substantially vertical face 166.

Down tube 118 includes a down tube extension 162 protruding forward fromthe lower end of the down tube to at least partially fill the spacebetween bottom bracket 124 and face 166 of crown 132. As discussedregarding FIG. 1, down tube extension 162 may have a generallytriangular profile when viewed from the side. A forward face 164 ofextension 162 is adjacent face 166 of crown 132. As with extension 62,one or more additional mechanisms may be incorporated into extension162, such as the damper assembly described below in Section E.

An airfoil-shaped combined cross section similar to the one shown inFIG. 3 is also created with wheel 128, mid portion 136 of crown 132, anddown tube 118. Wheel 128 includes a rim 174 and a tire 176. Rim 174 mayinclude any suitable bicycle wheel rim, including those described withrespect to rim 74. Wheel 128 may further include a braking system, whichin this example includes a rim brake 178 mounted on blade 140.

C. Additional Illustrative Bicycles Utilizing an Aerodynamic Front ForkAssembly

As shown in FIGS. 7-10, this section describes further examples of frontfork assembly 10 incorporated into two different illustrative bicycles.Except where specifically depicted or described otherwise, components ofthe forks and bikes described in this Section C may be substantively andfunctionally identical to corresponding components described in SectionA.

With reference to FIGS. 7 and 8, a front fork assembly 210 is anotherexample of the front fork assembly described in the Overview above, andmay be substantially identical to fork assembly 10 of Section A.

FIG. 7 is a side elevation view of a bicycle 212 suitable for use withfront fork assembly 210. FIG. 8 is a sectional view of a front wheel ofbicycle 212, a portion of front fork assembly 210, and a down tube ofbicycle 212 having a controllable trailing edge portion, taken at line8-8 in FIG. 7 and showing the overall airfoil shape of this combinationof components.

With continuing reference to FIGS. 7-8, bicycle 212 includes forkassembly 210 and a frame 214. In this example, frame 214 comprisesmultiple frame elements, including a cantilevered top tube 216 and adown tube 218. Down tube 218 extends at an angle from a head tube 222 toa bottom bracket 224 of bicycle 212. In this example, a leading edge 226of down tube 218 is substantially linear.

A front wheel 228 of bicycle 212 is steerably coupled to frame 214 byfront fork 210. More specifically, front fork 210 includes a steerertube 230 pivotably coupled to head tube 222, and an elongate crown 232having a proximal end portion 234 coupled to the steerer tube, the crownextending generally parallel to down tube 218 through an intermediate ormid portion 236 to a distal end portion 238 behind front wheel 228. Oneor more (in this case two) fork blades 240 protrude in a generallyforward direction from distal end portion 238, and front wheel 228 isrotatably coupled to blades 240, e.g., by an axle of the wheel.

Crown 232 has a pair of side walls 242, 244 (also referred to as lateralfaces) extending continuously from a front face 246 that generallyfollows a curved outer circumference of front wheel 228 to a rear face248 that generally follows the front surface (i.e., leading edge 226) ofthe down tube. Crown 232 is sized and shaped such that the outerperimeter of the crown substantially fills a gap 250 between the frontwheel and the down tube. Substantially filling gap 250 may include anysuitable taking-up of the space between the wheel and the down tube, asdescribed above.

A narrow first space 252 exists between front face 246 of crown 232 andan outer diameter of front wheel 228. Similarly, a narrow second space254 is provided between rear face 248 of crown 232 and leading edge 226of down tube 218. First space 252 and second space 254 may have anysuitable dimensions, e.g., as described with respect to correspondingspaces above, and may vary from proximal portion 234 to distal portion238.

As described regarding FIG. 1, down tube 218 may include a down tubeextension 262 protruding forward from the lower end of the down tube toat least partially fill the space between bottom bracket 224 and distalportion 238 of crown 232.

FIG. 8 depicts a sectional view taken through wheel 228, mid portion 236of crown 232, and down tube 218, showing the overall aerodynamic shapeof the airfoil collectively formed by these components. Wheel 228includes a rim 274 and a tire 276, substantially as described above withrespect to Section A. Similarly, crown 232 is substantially as describedabove with respect to Section A. In this example, crown 232 includes aspacer 286, comprising a resilient material having a thicknessconfigured to at least partially fill space 254 between the crown andthe down tube when the front wheel is aligned with the down tube. Spacer286 has a rear-facing outer surface 290 comprising a resilient pile.

The main body of down tube 218, when viewed in section, has a Kammprofile with a blunt or squared-off trailing edge 266 forming atruncated teardrop shape. Down tube 218 further includes a controllabletrim tab 268, also referred to as an airfoil extension, as shown inFIGS. 7 and 8. Trim tab 268 may include any suitable structureconfigured to extend and streamline down tube 218. Trim tab 268 ispivotable on a long axis, as indicated in FIG. 8. An angle of airfoilextension 268 may be manually and/or automatically controllable, e.g.,using a controller and actuator 270. In some examples, trim tab 268 maybe configured to pivot freely in the airstream (e.g., feathering). Insome examples, trim tab 268 may be held at a fixed angle, e.g., by afriction hold mechanism.

In some embodiments, an angle of trim tab 268 may be automaticallycontrolled in response to a sensed wind speed and/or direction, e.g., byplacing an onboard wind sensor 272 in communication with controller andactuator 270. The angle of trim tab 268 may be controlled, e.g., toreduce turbulence and/or to bend air flow to create a component ofthrust (similar to a sail or a wing).

Turning to FIG. 9, a front fork assembly 310 is depicted as part ofanother bicycle, namely bicycle 312, and shown in side elevation view.Front fork 310 is substantially identical to front forks 10 and 210, andall corresponding components are as described above. Bicycle 312 issubstantially identical to bicycle 212, with all correspondingcomponents as described above, except that a down tube 318 of bicycle312 does not include the trim tab.

FIG. 10 depicts a sectional view taken through a wheel 328, a crown 332of front fork 310, and down tube 318, showing the overall aerodynamicshape of the airfoil collectively formed by these components. Wheel 328includes a rim 374 and a tire 376, and crown 332 is substantially asdescribed above with respect to Section A. Crown 332 includes a spacer386, comprising a resilient material having a thickness configured to atleast partially fill a space between the crown and the down tube whenthe front wheel is aligned with the down tube. Spacer 386 again has arear-facing outer surface 390 comprising a resilient pile. The main bodyof down tube 318 has a Kamm profile with a blunt or squared-off trailingedge 366 forming a truncated teardrop shape. Unlike down tube 218, thisembodiment includes no trim tab.

D. Third Illustrative Aerodynamic Front Fork Assembly and Bicycle

As shown in FIGS. 11-12, this section describes a third illustrativeembodiment of a front fork assembly, namely fork assembly 410. Frontfork assembly 410 is another example of the front fork assemblydescribed in the Overview above, and may be similar to fork assembly 10of Section A and 110 of Section B. Except where specifically depicted ordescribed otherwise, components of the fork and bike described in thisSection D may be substantively and/or functionally identical tocorresponding components described in Sections A and B.

FIG. 11 is a perspective view of a bicycle 412, which includes forkassembly 410 and a frame 414. In this example, frame 414 comprisesmultiple frame elements, including a top tube 416 and a down tube 418,forming a Y-shaped frame similar to frame 214 described above. Down tube418 extends at an angle from a head tube 422 to a bottom bracket 424 ofbicycle 412. A leading edge 426 of down tube 418 is substantiallylinear.

As with bicycle 12, a front wheel 428 of bicycle 412 is steerablycoupled to frame 414 by front fork 410. An elongate crown 432 has aproximal end portion 434 coupled to the steerer tube. The crown extendsgenerally parallel to down tube 418 through an intermediate or midportion 436 to a distal portion 438 behind front wheel 428. One or morefork blades 440 protrude in a generally forward direction from distalend portion 438, and front wheel 428 is rotatably coupled to blades 440.In this example, blades 440 are angled similar to the approximatelyten-degree angle of blades 40.

As with crown 32, crown 432 has a pair of side walls 442 (also referredto as lateral faces) extending continuously from a front face 446 thatgenerally follows a curved outer circumference of front wheel 428 to arear face 448 that generally follows the front surface (i.e., leadingedge 426) of the down tube. Crown 432 is sized and shaped such that theouter perimeter of the crown substantially fills a gap 450 between thefront wheel and the down tube, as described in Section A above.

A long axis 456 of each blade 440 of fork assembly 410 is angleddownward slightly, from the proximal to the distal end. As with blades40, the concern regarding interference with a set of rotating cranks 458and pedals 460 remains, which is one reason contributing to the forkangle being greater than horizontal.

An airfoil-shaped combined cross section similar to the one shown inFIGS. 3 and/or 10 is also created with wheel 428, mid portion 436 ofcrown 432, and down tube 418. Wheel 428 includes a rim 474 and a tire476. Rim 474 may include any suitable bicycle wheel rim, including thosedescribed with respect to rim 74. Wheel 428 may further include abraking system, which in this example includes a rim brake 478 mountedon blade 440.

FIG. 12 is a front elevation view of bicycle 412. Among other things,FIG. 12 depicts the reduced front-facing area of fork blades 440 withrespect to airstream exposure.

E. Illustrative Damping Assembly for an Aerodynamic Front Fork Assembly

As shown in FIGS. 13-15, this section describes an illustrativeadjustable damping mechanism 500, suitable for use with aerodynamicfront fork assemblies disclosed herein. Damping mechanism 500 may bereferred to as a damper assembly. Damping mechanism 500 may include anysuitable apparatus configured to apply a damping surface to the crown ofan aerodynamic front fork to reduce vibration-induced shuddering of thecrown and/or fork blades. In this example, damping mechanism 500 isconfigured to apply a damping force from the bicycle frame to theaerodynamic fork, while maintaining steerability of the front wheel.

FIG. 13 is a partial side elevation view of a front fork 502 and bicycleframe 504 taken near the proximal ends of the fork blades, showing adistal end portion 506 of a crown 508. A down tube 510 and down tubeextension 512 are also depicted adjacent to fork 502. Part of a wheel514 is shown, which is coupled to fork blade 516. FIGS. 14 and 14 aresectional views as indicated in FIG. 13.

Damping mechanism 500 may be mounted or incorporated into down tubeextension 512, which corresponds to extensions 62, 162, 262 describedabove. Damping mechanism 500 includes an adjustable-height damper pad518, which is a resilient or compressible pad configured to apply adamping force to distal end portion 506 of the crown. The height ofdamper pad 518 (i.e., the distance it protrudes from extension 512toward distal end 506) may be adjustable manually, such as by anactuator. In some examples, such as the one depicted in FIGS. 13-15, theactuator comprises an axially fixed rotatable thumb wheel 520 on athreaded stem 522 attached to a damper plate 524. Damper plate 524 isconfigured to hold the pad, and may be coupled to a guide pin 526configured to prevent plate 524 from spinning freely. In some examples,the height of damper pad 518 may be automatically adjusted by anactuator controller (not shown).

F. Illustrative Method of Manufacturing an Aerodynamic Front Fork for aBicycle

This section describes steps of an illustrative method for manufacturingan illustrative aerodynamic front fork for a bicycle in accordance withaspects of the present disclosure; see FIG. 16. This example of a methodis not intended to be limiting in any sense, as many other suitablemethods or variations may be utilized. Aspects of front fork assembliesand related systems described above may be included in the method stepsdescribed below. Where appropriate, reference may be made to componentsand systems that may be used in carrying out each step. These referencesare for illustration, and are not intended to limit the possible ways ofcarrying out any particular step of the method.

FIG. 16 is a flowchart illustrating steps performed in an illustrativemethod 550, and may not recite the complete process or all steps of themethod. Although various steps of method 550 are described below anddepicted in FIG. 16, the steps need not necessarily all be performed,and in some cases may be performed in a different order than the ordershown.

Step 552 of method 550 includes building or generating a core for thecrown of the fork assembly, wherein the core is shaped and sized asdescribed above (e.g., see FIGS. 1, 2, 5, 6). This step may include anysuitable materials and steps, such as carving or shaping of foam orother material blocks, injection molding of plastics and the like,casting, CNC machining, molding, and/or any combination of these. Forexample, step 552 may include step 554, wherein a plurality of end grainbalsa wood blocks are stacked and adhered together, e.g., with thedirection of the grain along the long axis of the stack. Step 556 thenincludes machining the assembled blocks into the shape of the crowncore. For example, the crown core may have a curved profile along onelong edge and a linear profile along an opposing long edge. A front facemay be concave. Ends of the crown core may also be concave, to receiveadditional components (e.g., steerer tube, blade stub) at a later stepin the process.

Step 558 of method 550 includes orienting and assembling the crown corewith a steerer tube receiver (at the proximal end) and a stub tubereceiver (at the distal end) to create a crown assembly (e.g., see FIG.5). Each receiver may include any suitable materials, and may be agenerally cylindrical or frustoconical tube comprising carbon fiber.Inner diameters of each of the tubes may be slightly larger than thecorresponding components to be received therein. The steerer tubereceiver may be slightly larger than the steerer tube, and the stub tubereceiver may be slightly larger than the blade assembly stub tube. Thereceivers permit precise alignment of components during a later bondingstep, and permit the separate fabrication or acquisition of a steerertube and blade assembly.

Step 560 of method 550 includes encasing the crown assembly in acomposite shell. This step may include any suitable carbon fiber layuptechnique or methodology. For example, step 560 may include step 562wherein carbon fiber strands and epoxy resin are oriented over the crownassembly in multiple directions. Step 564 may then include curing thecarbon fiber and epoxy resin in a mold, under pressure.

Step 566 of method 550 includes connecting, aligning, and bonding thesteerer tube and blade assembly to the encased crown assembly (e.g., seeFIG. 5). The blade assembly may include any suitable fork blades (e.g.,carbon fiber blades) connectable to the crown assembly, e.g., byinserting a stub tube of the fork blades into the stub tube receiver ofthe crown assembly. The fork blades are connected to the distal portionof the crown assembly, oriented transverse to a long axis of the crown.This step results in a unitary, stiff fork assembly, with fork bladesconfigured to extend in a generally forward direction when installed ona bicycle.

In some examples, the fork assembly may be skinned, e.g., by applying athin layer of material to the fork assembly. This layer may comprise anysuitable material or combination of materials, such as plastic,epoxy-reinforced cardboard, etc. Any suitable method may be used, suchas vacuum forming or hand-application. In some examples the layer isapplied only at junctions between components, e.g., to smooth thetransition between the crown and the fork blades. In some examples,carbon fiber strands may be applied and cured after connecting the forkblades and the crown assembly.

This method results in an aerodynamic front fork assembly having anelongate crown extending at an angle from a steerer tube. The crowncomprises a core encased in a composite shell, such that the core has alengthwise arcuate front face, a rear face configured to follow the downtube of a bicycle (e.g., generally linear and planar), and two opposingside faces. The crown is securely coupled to a fork blade assemblyhaving one or more fork blades, such that the one or more fork bladesextend from the distal end portion of the crown at an angle that istransverse to a long axis of the crown.

G. Additional Examples and Illustrative Combinations

This section describes additional aspects and features of aerodynamicforks and related systems in accordance with the present disclosure,presented without limitation as a series of paragraphs, some or all ofwhich may be alphanumerically designated for clarity and efficiency.Each of these paragraphs can be combined with one or more otherparagraphs, and/or with disclosure from elsewhere in this application,in any suitable manner. Some of the paragraphs below expressly refer toand further limit other paragraphs, providing without limitationexamples of some of the suitable combinations.

A0. A front fork for a bicycle, the front fork comprising:

a steerer tube;

an elongate crown coupled to the steerer tube, the crown extending at anoblique angle from a proximal end portion adjacent the steerer tubethrough an intermediate portion to a distal end portion, and extendingfrom a rear face to a front face, the rear face having a linearlengthwise profile, and the front face having an arcuate lengthwiseprofile; and

one or more fork blades extending in a generally forward direction fromthe distal end portion of the crown, each of the one or more fork bladeshaving a distal end;

wherein the front fork is configured to receive a front wheel of abicycle, the front wheel being received by the distal ends of the one ormore fork blades, the rear face of the crown generally conforming to anadjacent down tube of the bicycle, and the front face of the crown beingadjacent to an outer perimeter of the front wheel, such that the crownsubstantially fills a gap between the front wheel and the down tube.

A1. The front fork of A0, wherein a distance between the front face andthe rear face of the crown is greater at the proximal portion and at thedistal portion than at the intermediate portion of the crown.

A2. The front fork of any of paragraphs A0 through A1, wherein the crowncomprises an outer shell.

A3. The front fork of A2, wherein the outer shell comprises a compositematerial.

A4. The front fork of A3, wherein the composite material is carbonfiber.

A5. The front fork of A2, wherein the crown further comprises a solidinner core.

A6. The front fork of A5, wherein the solid inner core comprises balsawood.

A7. The front fork of A6, wherein the solid inner core comprises aplurality of end grain balsa wood blocks adhesively connected together.

A8. The front fork of A6, wherein the balsa wood is oriented such that agrain of the balsa wood is generally parallel to an elongate axis of thecrown.

A9. The front fork of any of paragraphs A0 through A8, furthercomprising a spacer coupled to the rear face of the crown, the spacerhaving an outer surface comprising a resilient pile and a thicknessconfigured to at least partially fill a gap between the crown and thedown tube when the front wheel is aligned with the down tube.

A10. The front fork of any of paragraphs A0 through A9, wherein thefront face of the crown is concave, with a curvature oriented transverseto the arcuate lengthwise profile of the front face.

A11. The front fork of any of paragraphs A0 through A10, wherein thecrown is configured to form an airfoil when aligned with the front wheeland the down tube.

A12. The front fork of A11, wherein the crown has opposing lateral facesconfigured and spaced from each other such that substantially continuousopposing lateral surfaces are formed from a leading edge of the frontwheel to a trailing edge of the down tube.

A13. The front fork of any of paragraphs A0 through A12, wherein a longaxis of the steerer tube passes forward of the distal ends of the one ormore fork blades.

A14. The front fork of any of paragraphs A0 through A13, wherein therear face of the crown has a substantially linear profile.

B0. A bicycle comprising:

a frame including a down tube;

a front wheel steerably coupled to the frame by a front fork, the frontfork comprising:

-   -   a steerer tube pivotably coupled to a head tube of the frame;    -   a crown having a proximal end portion coupled to the steerer        tube, the crown extending generally parallel to the down tube to        a distal end portion behind the front wheel, the crown having a        pair of side walls extending continuously from a front face that        generally follows a curved outer circumference of the front        wheel to a rear face that generally follows a linear front        surface of the down tube, wherein the crown substantially fills        a gap between the front wheel and the down tube; and    -   one or more elongate fork blades protruding in a generally        forward direction from the distal end portion of the crown, the        front wheel being rotatably coupled to the one or more fork        blades.

B1. The bicycle of B0, wherein, wherein a long axis of the one or morefork blades defines a fork angle with respect to horizontal, and thefork angle is less than approximately forty degrees.

B2. The bicycle of B1, wherein the fork angle is less than approximatelyfifteen degrees.

B3. The bicycle of B2, wherein the fork angle is approximately zerodegrees.

B4. The bicycle of any of paragraphs B0 through B3, wherein the downtube has a non-circular cross section, and a combination of the frontwheel, the crown of the fork, and the down tube forms an airfoil whenthe front wheel is aligned with the frame.

B5. The bicycle of B4, wherein aligned lateral sides of the wheel, thecrown, and the down tube form a substantially continuous aerodynamicsurface.

B6. The bicycle of any of paragraphs B0 through B5, wherein the rearface of the crown is spaced no greater than approximately ½ (e.g., ⅜) ofan inch from the down tube when the crown and the down tube are aligned.

B7. The bicycle of any of paragraphs B0 through B6, wherein a length ofthe front face of the crown is spaced no greater than approximately ½ ofan inch from the front wheel.

B8. The bicycle of any of paragraphs B0 through B7, wherein the frontface of the crown is concave from side wall to side wall.

B9. The bicycle of any of paragraphs B0 through B8, wherein the crowncomprises an outer shell.

B10. The bicycle of B9, wherein the outer shell comprises a compositematerial.

B11. The bicycle of B10, wherein the composite material is carbon fiber.

B12. The bicycle of B9, wherein the crown further comprises a solidinner core.

B13. The bicycle of B12, wherein the solid inner core comprises balsawood.

B14. The bicycle of B13, wherein the solid inner core comprises aplurality of end grain balsa wood blocks adhesively connected together.

B15. The bicycle of B12, wherein the balsa wood is oriented such that agrain of the balsa wood is generally parallel to an elongate axis of thecrown.

B16. The bicycle of any of paragraphs B0 through B15, further comprisinga spacer coupled to the rear face of the crown, the spacer having anouter surface comprising a resilient pile and a thickness thatsubstantially fills a gap between the crown and the down tube when thefront wheel is aligned with the down tube.

B17. The bicycle of any of paragraphs B0 through B16, wherein a longaxis of the steerer tube passes forward of the distal ends of the one ormore fork blades.

B18. The bicycle of any of paragraphs B0 through B17, the down tubefurther comprising an extension protruding forward below the distal endportion of the crown, such that an upper face of the extension isadjacent a lower face of the distal end portion of the crown.

B19. The bicycle of B18, wherein the down tube extension furthercomprises a damper assembly having an adjustable-height damper padconfigured to apply a damping force to the distal end portion of thecrown.

B20. The bicycle of B19, wherein a height of the damper pad is manuallyadjustable.

B21. The bicycle of any of paragraphs B0 through B20, wherein the frontfork is torsionally stiff.

C0. A bicycle comprising:

a frame including a down tube;

a front wheel steerably coupled to the frame by a front fork, the frontfork comprising:

-   -   a steerer tube pivotably coupled to a head tube of the frame;    -   a crown having a proximal end portion coupled to the steerer        tube, the crown extending generally parallel to the down tube to        a distal end portion behind the front wheel, the crown having a        pair of side walls extending continuously from a front face that        generally follows a curved outer circumference of the front        wheel to a rear face that generally follows a front surface of        the down tube, wherein the crown substantially fills a gap        between the front wheel and the down tube; and    -   one or more elongate fork blades protruding in a generally        forward direction from the distal end portion of the crown, the        front wheel being rotatably coupled to the one or more fork        blades.

C1. The bicycle of C0, wherein the down tube has an airfoilcross-section with a generally squared-off trailing edge.

C2. The bicycle of any of paragraphs C0 through C1, further comprising apivotable trim tab extending from the trailing edge of the down tube.

C3. The bicycle of C2, wherein an angle of the pivotable trim tab isautomatically adjustable in response to a sensed wind direction and windspeed.

C4. The bicycle of any of paragraphs C0 through C3, wherein the frontsurface of the down tube is substantially linear.

C5. The bicycle of any of paragraphs C0 through C4, wherein the crowntakes up at least approximately seventy-five percent of the gap betweenthe front wheel and the down tube

Advantages, Features, Benefits

The different embodiments and examples of the aerodynamic front forkassemblies described herein provide several advantages over knownsolutions. For example, illustrative embodiments and examples describedherein reduce aerodynamic drag on the bicycle by placing the wheelsupport blades at a near horizontal angle with the blade-supportingcrown component behind the front wheel, and further by mostly fillingthe space between the wheel and the down tube of the bicycle frame.

Additionally, and among other benefits, illustrative embodiments andexamples described herein provide a damping mechanism to controlroad-induced vibrations or oscillations and cross wind effects andenable a smoother ride than with conventional front wheel supportdesigns.

Additionally, and among other benefits, illustrative embodiments andexamples described herein permit incorporation of the fork assembly withexisting bicycle frame designs and components so that a bicycle'sperformance can be improved without extensive expense and labor.

Additionally, and among other benefits, illustrative embodiments andexamples described herein enable the use of either disc brakes or rimbrakes on the front wheel.

Additionally, and among other benefits, illustrative embodiments andexamples described herein may integrate a tool or storage space and afairing as a part of the damper mechanism housing.

Additionally, and among other benefits, illustrative embodiments andexamples described herein lower the center of gravity of the bicycle byrelocating fork components as compared with standard forks (i.e., bymoving the wheel support blades more in line with the front wheel axle).This consequently improves handling.

Additionally, and among other benefits, illustrative embodiments andexamples described herein create a novel and striking appearance. Thebasic form of the bicycle has not changed much for over one hundredyears. In one embodiment, the design is simplified and reduced to ahorizontal rider support platform and a horizontal wheel supportstructure connected by an inclined wing-like structure (see FIG. 11). Incontrast, existing designs usually consist of a visually-complex tubulardiamond frame and vertical fork assembly.

No known system or device can perform these functions. However, not allembodiments and examples described herein provide the same advantages orthe same degree of advantage.

CONCLUSION

The disclosure set forth above may encompass multiple distinct exampleswith independent utility. Although each of these has been disclosed inits preferred form(s), the specific embodiments thereof as disclosed andillustrated herein are not to be considered in a limiting sense, becausenumerous variations are possible. To the extent that section headingsare used within this disclosure, such headings are for organizationalpurposes only. The subject matter of the disclosure includes all noveland nonobvious combinations and subcombinations of the various elements,features, functions, and/or properties disclosed herein. The followingclaims particularly point out certain combinations and subcombinationsregarded as novel and nonobvious. Other combinations and subcombinationsof features, functions, elements, and/or properties may be claimed inapplications claiming priority from this or a related application. Suchclaims, whether broader, narrower, equal, or different in scope to theoriginal claims, also are regarded as included within the subject matterof the present disclosure.

What is claimed is:
 1. A front fork for a bicycle, the front forkcomprising: a steerer tube; an elongate crown coupled to the steerertube, the crown extending at an oblique angle from a proximal endportion adjacent the steerer tube through an intermediate portion to adistal end portion, and extending from a rear face to a front face, therear face having a linear lengthwise profile, and the front face havingan arcuate lengthwise profile; and one or more fork blades extending ina generally forward direction from the distal end portion of the crown,each of the one or more fork blades having a distal end; wherein thefront fork is configured to receive a front wheel of a bicycle, thefront wheel being received by the distal ends of the one or more forkblades, the rear face of the crown generally conforming to an adjacentdown tube of the bicycle, and the front face of the crown being adjacentto an outer perimeter of the front wheel, such that the crownsubstantially fills a gap between the front wheel and the down tube. 2.The front fork of claim 1, wherein a distance between the front face andthe rear face of the crown is greater at the proximal portion and at thedistal portion than at the intermediate portion of the crown.
 3. Thefront fork of claim 1, further comprising a spacer coupled to the rearface of the crown, the spacer having an outer surface comprising aresilient pile and a thickness configured to at least partially fill agap between the crown and the down tube when the front wheel is alignedwith the down tube.
 4. The front fork of claim 1, wherein the front faceof the crown is concave, with a curvature oriented transverse to thearcuate lengthwise profile of the front face.
 5. The front fork of claim1, wherein the crown is configured to form an airfoil when aligned withthe front wheel and the down tube.
 6. The front fork of claim 5, whereinthe crown has opposing lateral faces configured and spaced from eachother such that substantially continuous opposing lateral surfaces areformed from a leading edge of the front wheel to a trailing edge of thedown tube.
 7. The front fork of claim 1, wherein the rear face of thecrown has a substantially linear profile.
 8. A bicycle comprising: aframe including a down tube; a front wheel steerably coupled to theframe by a front fork, the front fork comprising: a steerer tubepivotably coupled to a head tube of the frame; a crown having a proximalend portion coupled to the steerer tube, the crown extending generallyparallel to the down tube to a distal end portion behind the frontwheel, the crown having a pair of side walls extending continuously froma front face that generally follows a curved outer circumference of thefront wheel to a rear face that generally follows a linear front surfaceof the down tube, wherein the crown substantially fills a gap betweenthe front wheel and the down tube; and one or more elongate fork bladesprotruding in a generally forward direction from the distal end portionof the crown, the front wheel being rotatably coupled to the one or morefork blades.
 9. The bicycle of claim 8, wherein, wherein a long axis ofthe one or more fork blades defines a fork angle with respect tohorizontal, and the fork angle is less than approximately forty degrees.10. The bicycle of claim 9, wherein the fork angle is less thanapproximately fifteen degrees.
 11. The bicycle of claim 8, wherein acombination of the front wheel, the crown of the fork, and the down tubeforms an airfoil when the front wheel is aligned with the frame.
 12. Thebicycle of claim 8, wherein the rear face of the crown is spaced nogreater than approximately ½ of an inch from the down tube when thecrown and the down tube are aligned.
 13. The bicycle of claim 8, whereinthe front face of the crown is concave from side wall to side wall. 14.The bicycle of claim 8, wherein the crown has an outer shell comprisinga composite material.
 15. The bicycle of claim 14, wherein the crownfurther comprises a solid inner core.
 16. A bicycle comprising: a frameincluding a down tube; a front wheel steerably coupled to the frame by afront fork, the front fork comprising: a steerer tube pivotably coupledto a head tube of the frame; a crown having a proximal end portioncoupled to the steerer tube, the crown extending generally parallel tothe down tube to a distal end portion behind the front wheel, the crownhaving a pair of side walls extending continuously from a front facethat generally follows a curved outer circumference of the front wheelto a rear face that generally follows a front surface of the down tube,wherein the crown substantially fills a gap between the front wheel andthe down tube; and one or more elongate fork blades protruding in agenerally forward direction from the distal end portion of the crown,the front wheel being rotatably coupled to the one or more fork blades.17. The bicycle of claim 16, wherein the down tube has an airfoilcross-section with a generally squared-off trailing edge, the bicyclefurther comprising a pivotable trim tab extending from the trailing edgeof the down tube.
 18. The bicycle of claim 17, wherein an angle of thepivotable trim tab is automatically adjustable in response to a sensedwind direction and wind speed.
 19. The bicycle of claim 16, wherein thefront surface of the down tube is substantially linear.
 20. The bicycleof claim 16, wherein the crown takes up at least approximatelyseventy-five percent of the gap between the front wheel and the downtube.